Assessment of tunnel stability based on short- and long-term parameters

Abstract

Tünel stabilitesinin kısa ve uzun dönem parametreleri ile değelendirilmesi

Öz

Günümüzde zayıf zeminler ile fay zonu içerisinde açılan tünellerin sayısına bağlı olarak, bu tür ortamlarda tünelcilik açısından yaşanan sorunlar ve çözüm önerileri gittikçe artmaktadır. Aktif tektonik zonları içeren ülkemizde, fay zonlarında açılan tünellerden elde edilen tecrübeler tünelcilik açısından büyük öneme sahiptir. Yüksek hızlı tren projeleri kapsamında açılan tünellerde güzergahın kurp yarıçaplarının büyük olması sebebiyle, güzegah seçiminde ciddi sınırlamalar bulunmaktadır. Bu sebeple zayıf zeminler ile fay zonlarından kaçınılması çoğu zaman mümkün olamamaktadır. Fay zonu ve/veya zayıf zon geçişlerinde çoğu zaman özel destek sistemi tasarımı gerekmekte olup, tünel kazıları sırasında karşılaşılan sorunların çoğunluğu bu kesimlerde yaşanmaktadır. Sıklıkla karşılaşılan sorunlara ek olarak, zayıf zeminlerde kısa ve uzun dönem parametrelerine göre de destek sistemlerinin değerlendirilmesi de gerekmektedir. Özellikle tünel aynasında yapılan ayna zemin çivileri ile sürenlerin kısa dönem parameterlerine göre değerlendirilmesi gerekirken iç kaplamanın ise uzun dönem parametrelerine göre değerlendirilmesi gerekmektedir. Tüm bu hususlar dikkate alınarak bu çalışmada, Ankara-İstanbul Yüksek Hızlı Tren projesi kapsamında açılan T21 tünelinde karşılaşılan fay zonu geçişinde uygulanan destek sistemleri incelenmesi, FLAC 3d programı ile kısa ve uzun dönem parametrelerine göre analitik çözümlemeler ile 3 boyutlu nümerik analizler yapılması ve sonuçların tünelcilik pratiği açısından tartışılması amaçlanmıştır.

Anahtar Kelimeler

• fay zonu
• tünel
• 3 boyutlu nümerik analiz
• kısa ve uzun dönem zemin parametreleri

Kaynakça

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